context: the speech rate is one of the parameters considered when investigating speech fluency and is an important variable in the assessment of individuals with communication complaints. objective: to correlate the stuttering severity index with one of the indices used for assessing fluency/speech rate. design: cross-sectional study. setting: fluency and fluency disorders investigation laboratory, faculdade de medicina da universidade de s？o paulo. participants: seventy adults with stuttering diagnosis. main measurements: a speech sample from each participant containing at least 200 fluent syllables was videotaped and analyzed according to a stuttering severity index test and speech rate parameters. results: the results obtained in this study indicate that the stuttering severity and the speech rate present significant variation, i.e., the more severe the stuttering is, the lower the speech rate in words and syllables per minute. discussion and conclusion: the results suggest that speech rate is an important indicator of fluency levels and should be incorporated in the assessment and treatment of stuttering. this study represents a first attempt to identify the possible subtypes of developmental stuttering. definition: objective tests that quantify diseases are important in their diagnosis, treatment and prognosis.